This invention relates to meters used by utilities to measure usage of electrical power, gas, or water by a consumer at whose premises the meter is installed, and more particularly, to tamper detection apparatus used to determine when a customer intentionally tries to tamper with or bypass the meter, or when someone swaps the meter with another meter.
Utility meters installed at a person's home or business are used by utilities for billing purposes. The meter measures consumption of the service provided and a statement, invoice, or bill to the customer is generated based upon the amount of consumption. A watt-hour meter, for example, is used to measure and record electrical energy consumption. The meter is usually either an electromechanical or electronic type meter and has a 4, 5 or 6 digit counter dial on its face for indicating electrical energy usage by the customer. Electrical service to the home or business is routed through the meter with a dial counter reading advancing in proportion to the amount of energy consumed.
For many years, an electrical meter was periodically (monthly) read by a meter reader who went to the home or business and recorded the current dial reading. This reading was then compared to the previous reading and a bill to the customer was calculated based upon the difference between the two readings. Now, due to advances in meter technology, a meter can be remotely read. With such meters, a signal indicative of energy usage (as well as certain other information related to the meter, power usage, quality of available power, etc.) is transmitted from the meter to the utility company. This information may be transmitted over electrical power lines, telephone lines, as a radio frequency signal, or by other means. The technology which allows this to be accomplished is commonly referred to as “Automated Meter Reading” or AMR, and includes electronic circuitry which captures, generates, stores and transmits the data. In this mode of operation, an AMR capable meter (hereafter referred to as an “AMR”) functions as a transponder. The meter, whether a conventional meter or AMR, is electrically connected between the utility company's power supply and the customer's home or business. Typically, the meter, which is provided by the utility, has a housing with one or more male connector plugs which are inserted into female connectors incorporated in a socket base to which the meter is mounted so to electrically connect the utility company's power supply side with the customer's power side.
Increased use of AMRs has reduced site visits by meter readers. It has also provided opportunities for someone to tamper with the meter. A common form of tampering is a customer swapping their AMR with that of someone who uses less electricity. For example, someone with a summer home is usually away from it during the winter, so energy consumption at the dwelling is very low compared to that of a house occupied year around. It is not unknown for a dishonest customer to swap his meter with that installed at the summer home and receive a significantly lower electric bill than they otherwise would receive. The part time resident, of course, receives a much higher electric bill. This type of swapping is possible because most meters used in this country are of the plug and socket type described above. As can be inferred from the foregoing, the two basic steps in meter tampering are 1) physical removal of the meter from its socket (disconnection), and 2) its reinstallation in the same or another socket (re-connection). Typically meters cannot be tampered with without first removing them from their sockets.
Other things people have known to do are to remove the meter and subsequently reinstall it such that the meter no longer reads the “true” electrical usage, but reads a significantly lower usage. During the removal time, some type of by-pass is employed so power still reaches the facility. It is also known by some dishonest persons to reverse rotation of the dials of a meter so to show negative power usage.
Because utilities are aware of the types of practices described above, they have taken steps to detect such activities. For example, meter removal can be detected using commercially available devices such as a ball or tilt switch, magnet and reed switches, moving ball and light interrupters, mercury switches, liquid filled tilt sensors, accelerometers, and piezoelectric sensors which sense vibrations as the meter is moved. Those skilled in the art will understand that while these various sensors are effective in sensing meter movement associated with its removal and reinstallation, something else must also be done. This is because current sensors are sufficiently sensitive that in addition to sensing movement of the meter as it is being removed, they will also sense other occurrences such as a foreign object striking the meter or its supporting structure (e.g., a wind blown rock). When these incidents, which are unrelated to attempts to tamper with the meter are reported, they create, in effect, false alarms. Since these non-tampering events will occur much more frequently than an actual tampering, the resultant false alarms could overwhelm those at the utility responsible for dealing with tampering incidents. Accordingly, any apparatus used with the meter must be able to recognize and distinguish actual tampering from these other occurrences.